The most recent mature leaves that growers had typically been advised to sample were fairly near the center of the whorl. When analyzed, these leaves consistently showed low calcium concentrations, but the outer perimeter leaves indicated the presence of adequate levels. Agronomists concluded that, for a crop like lettuce, it is critically important to define more precisely which leaf should be collected for a tissue sample.

Results of the field study helped the Agronomic Services Division provide more accurate tissue sampling guidelines for lettuce. The division now advises growers to collect the outermost, undamaged leaf. This leaf is practical because it is easy to identify and its nutrient content correlates more closely with the division’s established sufficiency ranges for calcium. The newly refined guideline should eliminate false diagnoses of low calcium levels.

“That’s one of the benefits of the Agronomic Division having a dedicated Field Services Section,” Hall said. “We are in direct contact with growers throughout the state. We hear feedback. We relay reactions and concerns back to our office and laboratory staff. We have an ongoing dialogue that helps both the division and its clients.”

Growers such as Bill Hering rely on NCDA&CS for precise nutrient management data and feel invested in the service. “Tissue analysis and soil test data help us optimize fertilization, input costs and yield. You can’t get too much of this kind of information,” Hering said. “We’re more than glad to work with the division to get things fine-tuned.”

The NCDA&CS Agronomic Services Division has regional agronomists statewide who can make on-site visits and evaluate suspected nutrient problems. Currently, they are working particularly closely with growers of lettuce and other plasticulture crops.

With the help of a grant from the North Carolina Tobacco Trust Fund Commission, agronomists visit and instruct plasticulture growers on how they can best use the division’s testing services to increase efficiency and productivity.

To contact the agronomist for your area, visit